just finished up my second week in hawaii on the big island. we stayed on the kona side, in captain cook (on kaleakakua bay to be exact). not as many reviews as my kauai post since we rented a house instead of staying in a hotel. here's the link to my kauai post http://www.chowhound.com/topics/469637
KTA is the main grocery store chain found all over the island. i am usually hesitant about buying fish from grocery stores and prefer to buy them from fish markets. however, all the fishermen send their catches of the day to the grocery stores here so everything we found were super fresh and sushi grade. there wasn't a huge variety of fish, just what was in season for december (ahi tuna, octopus, ono, marlin). also a nice selection of whole shrimp with the heads on. they also had several variations of poke available and ready to eat. the produce section wasn't so great. standard supermarket quality. farmer's markets and fruit stands were a better option for produce.
Choice Mart - we discovered this place on our second to last day of our stay. if you are staying south of kona, closer to the Captain Cook area then go to Choice Mart rather than KTA. i only say this because traffic on hwy 11/kuakini hwy is awful and it would take almost and hour of going 5 mph on hwy 11 to get to KTA. Choice Mart had all the same things as KTA, the fish was just as fresh and they had a larger selection of poke. i think it even may have been a tiny bit less expensive than KTA. also on hwy 11, but southbound (between 110 and109 mile markers i believe). no traffic and gorgeous views of the bay while driving.
Farmer's Markets/Fruit Stands:
Hit up the farmer's market in Kona (on corner of Alii Dr. and Hualailai). maybe 4 or 5 produce vendors with all similar selections. lots of strawberry papaya, local cukes, limes, lemons, avocados, tomatoes and other usual suspects. a lot of yummy custard fruit too. mangos were 2 for $5 so we didn't bother with them. the market also included many vendors of knick knacks, cheap ukeleles, jewelry, etc. overall a nice market and a great selection of produce. FYI, no farmer's markets are open on mondays and tuesdays. all run during the wed-sun stretch.
South Kona Fruit Stand:
This place was great. all certified organic produce, many unusual (to me) fruits and veggies. prices were pretty reasonable except for a few select items such as mission figs @ $.75 each. they sold hula girl coffee there at $30 a half pound (not sure if that is inflated or not though). they also offer fresh fruit smoothies, but didn't get a chance to try them. really nice people working there. i highly recommend checking them out if you can.
Ocean Sushi - on the Hilo side of the island. found this through our "Big Island Revealed" guidebook. no frills ambiance, just tables and chairs basically. very large fish and maki selection. the fish quality was SUPER fresh and delicious and the prices were extremely cheap to the point of suspicion (we couldn't complain though considering how expensive everything else was on the island). the uni was outstanding, which wasn't surprising considering that sea urchin could be seen all over the ocean floor while snorkeling. sushi dinner for 4, plus an order of shrimp tempura and 4 miso soups came to about $61 before tip. if you are in hilo i highly recommend this spot.
Jake's BBQ - on hwy 11 between the 105-106 mile markers i believe. it shares the same building/parking lot as Kona Seafood (which unfortunately was not that impressive the couple of times we stopped in there). there's a huge smoker out front that you can't miss. order and pickup at the window with picnic table seating. ordered half rack of ribs plate and bbq pork sandwich both of which came with baked beans and choice of coleslaw or potato salad. the half rack was gigantic, at least 8-10 ribs with a good inch and a half of meat on it. the ribs were most likely boiled first, then smoked and quickly grilled (if at all) then smothered with bbq sauce. i'm not an expert on bbq, but i was kind of dissapointed with them because they didn't have that sticky smoky flavor that i usually equate with bbq ribs thought the meat itself was moist and juicy. the sauce, beans and potato salad were great and the portion of ribs was absolutely ridiculous. the pulled pork sandwich was excellent and also huge. we ordered 2 half racks and 2 sandwiches between the 4 of us, but could have easily just shared one order of each and would have been fine. with a lemonade, bottle of water and mango smoothie came to around $50. we all fell in to serious post-bbq comas afterwards.
Donkey Balls - not a restaurant, but a coffee shop that sells chocolate covered macadamia nuts. pretty pricey, about $6 for a 5 oz. bag of balls, but we had to try them. both milk and dark chocolate, some with other flavors infused. we got the "salty balls". dark chocolate with a thin layer of salt over them. we couldn't resist chocolate salty balls (a la south park) so we shelled out the six bucks. they were great and provided hours of immature jokes.
sorry there weren't more restaurant reviews, but hopefully these will be somewhat helpful to someone. aloha!